Insects associated with the faecal pellets of the koala, Phascolarctos cinereus Goldfuss
Melzer, A, Schneider, MA & Lamb, D 1994, Australian Entomologist, vol. 21, no. 3, pp. 69-70.
In koala faecal pellets collected near Springsure, Queensland, insects that causing pellet damage and decomposition were identified. One beetle species (Ptinus sp.), two moth species (Argyrotoxa pompica and Blastobasis sp.) and four wasp species (Pycnobracon sp., Choeras sp., Diaulomorpha sp. and a pteromalid) were recovered from the faecal pellets.
The collected koala faecal pellets were put in sealed containers, which were equipped with a specific device for trapping emerging insects. The larvae of Ptinus sp. were found to bore through the inner part of the pellets, while the pupae of Argyrotoxa pompica were observed attaching to the surface of faecal pellets. The species of Blastobasis could not be further identified following recovery. For the Pycnobracon sp. observed, which is parasitic, the host could possibly be Ptinus sp. The species of Choeras found in this study was previously unknown, so further collection would help to identify its host. The host of the Diaulomorpha sp. was not identified, but it could be one of the moth species found in this study. Only one pteromalid specimen was recovered and, due to the poor body condition and lack of gaster, it was not possible to further identify the specimen beyond its subfamily.
Some of the insects mentioned above may be specialised in utilising the resources contained in koala faecal pellets. Koalas mainly feed on Eucalyptus leaves and produce hard and dry faecal pellets, which could be utilised by detritivores that adapt to Eucalyptus leaf litter.
The findings of this study reveal new detail about the ecological interactions that characterise koala habitats. Further, that insects have been found to damage and decompose koala faecal pellets has implications for survey techniques that use the presence or absence of scats as an indicator of the presence or absence of koalas, as this indication may not be reliable if detritivores are utilising this resource.
Summarised by Zilong Du
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